Erica Alvarado Salinas, 26, Alex Alvarado, 22, and Jose Angel Alvarado, 21, all American citizens, disappeared in 2014 while visiting their father in El Control, a small town near Matamoros, a Mexican city in the dangerous state of Tamaulipas, across the border from Brownsville, Texas.

Their bodies were found sixteen days later in a field east of Matamoros. They each had been shot in the head, and the bodies were badly decomposed. Jose Guadalupe Castaneda Benitez, 32, a friend from Mexico traveling with the siblings, was also killed.

According to the commission's report, witnesses said the four victims were forced into a vehicle belonging to the security detail of then-Matamoros Mayor Leticia Salazar Vázquez. Human rights investigators were also able to interview several men who reported being arrested the same day the American siblings disappeared. Many of them said they saw the group taken to an empty lot to be beaten and interrogated by the marines.

The commission determined that detention was illegal, as there was no order that would have explained their arrest. So far, state and federal authorities have denied involvement in the death of the victims. In a press release, the commission added that officials, marines, and state and federal police lied in statements to cover up the killings.

Of the arrests made by public servants of the Navy and Hercules Group on Oct. 13, 2014, no record exists, nor were they presented to any authority. There is not even an investigation involving (the victims), much less arrest orders or a complaint against them.

The commission delivered its findings to the Naval Secretariat, the governor of Tamaulipas, the mayor of Matamoros and Mexico’s National Security Commission. The murder case is still open. The government of Tamaulipas said they implemented human rights training for police in Mexico based on the report. They say the case is in the hands of federal prosecutors.

Tamaulipas has faced severe security concerns since the outset of Mexico's war against drug cartels in 2012. Recently, the U.S. State Department issued a “do not travel” advisory this month for Tamaulipas and four other Mexican states, "putting the regions on the same level as war-zones such as Syria, Yemen, and Afghanistan," as reported by The Guardian.

As highlighted by the San Antonio Express-News, a United Nations envoy reported in 2016 that “extrajudicial killings and excessive use of force by security officers persist” in Mexico.